Various methods are known in the art for performing active triangulation using structured light, or more specifically, coded light.
Broadly speaking, coded light methods aim at acquiring the three dimensional geometric structure of an object of interest by means of projecting a sequence of light patterns. A typical system features a camera and a projector with non-collinear optical axes, in which the projector is capable of illuminating the object with a pre-defined sequence of light patterns, and the camera capable of capturing the image of the object illuminated with these patterns, as shown in background art FIG. 1 and as described in greater detail below. The patterns are designed to form a code that encodes the position of an illuminated point on the object in the projector system coordinate. In each pixel seen by the camera the projector coordinate is thus also available, which allows reconstructing the three dimensional position of a point by means of triangulation. Triangulation assumes the knowledge of the geometric relations between the camera and projector systems of coordinates, which is recovered once by means of calibration. The reconstruction produces for each pixel of the camera image the x,y,z world coordinates, which can be represented in the form of three matrices (referred to as a geometry image). Typically, 8-12 patterns are used for accurate geometry reconstruction (though fewer patterns are possible for various applications, like a single pattern geometry reconstruction apparatus). In order to capture video rate (30 frames per second), the camera used for geometry acquisition has to be able to acquire at least 240-360 frames per second. In some applications, it is desired that the projected patterns would not be seen by human, which can be achieved by using invisible (e.g. infra-red) spectrum projector and camera with a sensor sensitive to this spectrum.
If one wishes to also acquire the photometric properties of the object (texture), it is possible to project fully dark and fully bright patterns, which are captured by the camera. The resolution of the texture image is the same as the resolution of the camera used for geometry acquisition.
By repeatedly projecting light patterns on a moving object, capturing the respective images, and performing reconstruction, one can obtain a three dimensional video of the object. This video can be compressed, transmitted, and stored.